Actuators including drive screws are well-known. In general, such actuators may include an electric motor having an output shaft coupled through a gear train to a worm gear. The worm gear may be in meshing engagement with the drive screw for causing rotation of the drive screw corresponding to rotation of the output shaft of the motor. In known configurations, the drive screw is fixed in position relative to the actuator housing, and rotation of the drive screw causes translation of a threaded drive nut along the length of the drive screw. The nut may be coupled to an object to be driven by the actuator.
The drive screw configuration provides advantages in establishing linear movement, i.e. of the drive nut, while being generally difficult to back-drive by applying an external force to the drive nut. In some configurations, however, a lengthy drive screw may be required to achieve the desired range of motion for the drive nut. This can result in a risk of bending of the drive screw and damage to the actuator. Also, a long drive screw may not be able to withstand high loads due to a limitation associated with the size of the thrust bearing that may be used with the screw.
Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications, and variations thereof will be apparent to those skilled in the art. Accordingly, it is intended that the claimed subject matter be viewed broadly.